We propose to study protein folding intermediates at two levels (a) under suitable equilibrium conditions where we can stabilize partially folded states of proteins and (b) by direct kinetic measurements using stopped-flow time-resolved SAXS. In Part (a) we will study three proteins where partially folded states have been characterized - apomyoglobin, staphylococcal nuclease and lysozyme. In the case of apomyoglobin it has been previously shown that several different partially folded states can exist at pH 2.0 with a degree of folding depending on the nature of the anion buffer used. Information on the degree of folding has been obtained by indirect methods and SAXS will provide direct geometrical information. For time-resolved studies we will measure the above proteins and also cytochrome c and interleukin-1b. Here we will be interested in observing the kinetics of shape changes.